Spark plug and ignition indicator system therefor



Jan. 24, 1961 F'. s. ANDERT 2,959,500

SPARK PLUG AND IGNITION INDICATOR SYSTEM THEREFOR Filed Aug. 2, 1957IINVENTOR Fran/r 5. Ana/en! ATTORNEY v SPARK PLUG AND IGNITION INDICATORSYSTEM THEREFOR Frank S. Andert, 877 Randolph, St. Paul, Minn.

Filed Aug. 2, 1957, Ser. No. 675,844

4 Claims. (Cl. 324-47) This invention relates to an improvement in sparkplugs and method of operating the same and deals particularly with aspark plug which provides a ready indication of whether or not the sparkplug is in operation.

A great number of different types of spark plugs have been produced fora multiplicity of purposes. Some such plugs have been produced whichprovide an alternate circuit which may be employed in the event onecircuit shall fail to operate. The present invention includes a sparkplug having a plurality of circuits, one of which acts to supply hightension current to the plug and the other two of which are connected toground. One of the last mentioned circuits is connected through anindicating light which permits a visual inspection of the operability ofthe plug so that at any time the operator of an internal combustionengine or the like may see at a glance whether or not all of the sparkplugs are operating correctly.

Various test circuits have been employed and some of these circuits havebeen built into the ignition systems of automobiles and the like.However, those systems with which I am familiar are supplied withcurrent from the vehicle distributor and use this current to provide avisual indication. While such systems show whether or not the sparkplugs are being supplied with current, they often do not actually showwhether the spark plug is operating. In any event, if they doactuallyshow operation or non-operation of the spark plug, they do this in anindirect manner.

A feature of the present invention resides in the provision of a sparkplug having a tubular conductor which extends through the core of thespark plug and which encloses an additional conductor. Ground terminalsare also provided in spaced relation to the tubular conductor so thatthe high tension current will jump between the ground connection and thetubular conductor. The third conductor which is enclosed within thetubular conductor is preferably connected to ground through a lampcapable of withstanding the current employed such as, for example, aneon bulb. As a result, spark may also jump from the tubular connectorto the enclosed electrode, this current forming a visual indication ofthe operability of the plug. As the light will not be illuminated unlessthe spark is jumping from the high tension terminal, this systemprovides an actual indication not only that the spark plug is beingsupplied with current, but also that the spark plug is actuallyoperating. As both the third electrode and the directly groundedelectrodes are connected to ground, a spark will be produced regardlessof the direction of travel of the spark produced.

A feature of the present invention resides in the provision of a sparkplug having three operable electrodes which are arranged in such amanner that while there is a tendency for the spark to jump from thetubular electrode to the directly grounded electrodes, the spark willalso jump to the third or enclosed electrode with sufficient regularityto provide a good indication of the operability of the plug. While it isa well known fact that electricity will normally follow the path ofleast resistance, unusual nited tates Paten "ice results may result whenhigh tension current is involved. Thus, while the general path ofelectricity is from the tubular electrode to the directly groundedelectrodes, there is sufficient discharge of electricity to the thirdelectrode to provide the necessary indication.

A further feature of the present invention resides in the production ofa spark plug having an outer grounded shell, a body of porcelain orsimilar material enclosed within the shell and projecting therefrom, atubular electrically conductive electrode extending through saidinsulator body, and an inner conductor enclosed within and insulatedfrom the tubular conductor. This type of spark plug makes the systemdescribed possible.

These and other objects and novel features of the present invention willbe more clearly and fully set forth in the following specification andclaims.

In the drawings forming a part of the specification:

Figure 1 is a cross sectional view through a spark plug showing thenovel construction thereof.

Figure 2 is a typical wiring diagram illustrating the manner in whichthe spark plug shown in Figure 1 may be used.

In general, much of the construction of the spark plug may beconventional. The spark plug is indicated in general by the letter A andincludes an outer metallic shell 10 which is preferably hexagonal inshape so that the spark plug may be engaged by a wrench or othersuitable tool. The lower portion 11 of the shell 10 is of slightlysmaller periphery arid includes external threads 12 by means of whichthe spark plug may be inserted into the engine block or the like. Ashoulder 13 is provided between the hexagonal portion 14 of the sparkplug shell and the lower threaded portion 11 thereof, this shoulderpermitting the insertion of a sealing washer or gasket between the sparkplug body and the engine block.

The lower portion 11 of the shell 10 is of one diameter internally asindicated at 15 and the sleeve or shell 10 is provided with a somewhatlarger diameter upper intermediate portion 16, a shoulder 17 thus beingformed between the two parts of different diameter. The upper end of theshell 10 is internally threaded as indicated at 19 to accommodate abushing 20. The bushing 20 is provided with a lower portion having acylindrical inner surface 21 which is of approximately the same diameteras the inner surface 15 and the coupling is provided with a taperedupper portion 22, the taper being on the inner surface of the coupling.

An insulator body 23 of porcelain or the like is provided with a taperedupper portion 24, a cylindrical portion 25 adjoining the upper taperedportion 24, a larger diameter portion 26 beneath the cylindrical portion25, and a tapered lower portion 27. Thus, the upper and lower ends ofthe insulator body are of somewhat smaller diameter than theintermediate portions thereof. The dimensions are such that the coupling20 is supported with its tapered inner surface 22 encircling the lowerportion of the tapered plug surface 24, the cylindrical portion 25fitting snugly Within the cylindrical inner surface 21 of the coupling20, the enlarged diameter portion 26 fitting snugly within the largerdiameter portion 16 of the shell 10 and with the tapered lower portion27 of the insulator body enclosed within the lower portion 11 of theshell 10. The insulator body extends with its lower end substantiallyflush with the lower end of the shell 10.

A tubular conductor 29 is embedded within the porcelain insulator 23,this conductor either being continuous throughout the length of theinsulator or incorporating a resistance element 30 between the twotubular end portions 29 and 31. A spring 32 or other connector may beinserted between the resistance 30 and one of the tubular parts 29 or 31so as to provide a continuous electrical connection from end to end ofthe plug. Spark plugs including resistors have possibly been employed inaircraft engines and the like where the proper operation of the plug isof vital importance. In the event the resistance element is notnecessary, the electrode may comprise a single tubular integral bodyextending from end to end of the plug.

An electrode 33 extends axially through an insulator 34 enclosed withinthe tubular electrode 29, 31. The insulation 34 holds the two electrodesin properly spaced relation to provide the necessary insulation effect.The electrode 33 preferably extends slightly below the end of theelectrode portion 31 as is indicated, to be more in the path of sparksjumping from the lower end of the tubular electrode 31 and the directlygrounded electrode 35. One or more such electrodes 35 may be employed.

The upper end of the tubular conductor 29 is externally threaded andprojects above the upper extremity of the insulator body 23. A screw cap36 or other suitable connector provides a means of connecting theconductor 29 to a flexible conductor such as 37 leading to thedistributor. Preferably, the upper end of the electrode 33 projects fromthe end of the insulator 34 as indicated at 39 and the electrode 39 isconnected to a conductive cap such as 49 which may be engaged by asuitable spring connector not illustrated in the drawings.

With reference now to Figure 2 of the drawings, a typical ignitionsystem employing the spark plugs A is indicated, the system beingemployed in a six cylinder engine for the purpose of illustration.Obviously, the ignition system can be changed or modified as the sourceof current or the source of the high tension electricity connected tothe spark plugs is not of importance in the present invention. However,in the arrangement illustrated, the battery 41 has one terminal groundedas indicated at 42. The other battery terminal is connected by aconductor 43 to one terminal of the low tension winding 44 of a sparkcoil 45. The other terminal of the coil 44 is connected by a conductor46 to ground at 47 through a current interrupting device 49 whichusually forms a part of the distributor. The current interrupting device49 normally includes one or'more pairs of breaker points which areoperated in timed relation to the distributor to provide a surge of hightension current each time the distributor connects the coil 45 to aspark plug.

The coil 45 also includes a high tension winding 50 connected to groundat 51, the other terminal of the high tension coil extending through theconductor 51' to the arm of the distributor 52. The distributor 52 issuccessively connected to contacts 53 which extend through thedistributor cap or are connected in any suitable way to the spark plugsby the conductor such as 54.

The conductors 54 are normally connected to the spark plug electrodes orconductors 29 while the electrodes 35 are grounded as indicated at 55.The inner or third electrodes 33 are shown connected by conductors 56 toindicator lamps 57, the other terminals of which are grounded asindicated at 59.

From the foregoing description it will be seen that as the engine isoperated, the distributor 52 directs current from the coil 50 to thevarious spark plugs in their proper succession. The major portion of thespark jumps from the tubular electrode 31 to the directly groundedelectrode or electrodes 35. However, sufiicient current also jumps tothe central electrode 33 to illuminate the associated light 57 toprovide an indication that the ignition system to the spark plugs is inoperation as well as the spark plug itself. Obviously, unless the sparkis jumping the gap between the various electrodes, no indication willtake place.

In accordance with the patent statutes, I have described the principlesof construction and operation of my improvement in spark plugs, andwhile I have endeavored to set forth the best embodiments thereof, Idesire to have it understood that changes may be made Within the scopeof the following claims without departing from the spirit of myinvention.

I claim:

1. A spark plug including an outer metallic shell, an insulator bodysupported within said shell, a tubular electrode extending through saidinsulator body, a second insulator body within said tubular electrode, asecond electrode extending through said second insulator Within saidtubular electrode, and a third electrode on said out r metallic shellextending transversely to the longitudinal axes of the tubular andsecondelectrodes into closely spaced relation with one end of said tubularelectrode and the adjacent end of said second electrode.

2. The construction described in claim 1 and in which thesecondelectrode within said tubular electrode projects beyond said one end ofsaid tubular electrode.

3. An ignition indicating system in combination with a spark plug havingan outer metallic shell, an insulator body supported within said shell,a tubular electrode extending through said insulator body, and anadditional electrode extending through said tubular electrode andinsulated therefrom, and an electrode on said outer metallic shellextending transversely to the longitudinal axes of said tubular andadditional electrodes into closely spaced relation to one end of saidtubular electrode and the adjacent end of said electrode extendingthrough said tubular electrode, a source of current connected to saidtubular electrode, the shell of said spark plug being grounded, and anindicator light between said electrode extending through said tubularelectrode and ground.

4. The construction described in claim 3 and in which said indicatinglight is a neon light.

References Cited in the file of this patent UNITED STATES PATENTS

